"Between WINE, VMware, BOCHs and ilk - not to mention the renewed focus on virtualisation we're now seeing - we're somewhat spoilt for choice when it comes to running Windows applications on Linux. But what about the other way around? Cygwin aside, there is another way."

We're already spoilt for choice the other way around too. VMware, Bochs and Qemu already run on Windows, and there is a Wine-like product called Line. How does this approach compare to all of these other choices?

What about coLinux?
"Cooperative Linux is the first working free and open source method for optimally running Linux on Microsoft Windows natively. More generally, Cooperative Linux (short-named coLinux) is a port of the Linux kernel that allows it to run cooperatively alongside another operating system on a single machine. For instance, it allows one to freely run Linux on Windows 2000/XP, without using a commercial PC virtualization software such as VMware, in a way which is much more optimal than using any general purpose PC virtualization software."

No. wxWidgets is a completely separate GUI toolkit that is independent of the operating system it's running on. It's great for cross-platform software but it doesn't help with software that's written for Gnome or KDE.

Q: Can LINA run on 64 bit processors? What about PowerPC Macs?
A: LINA is capable of running on 64 bit processors, but this architecture will not be supported in our initial release. Our initial release for Mac OS X will support both the PPC and Intel versions.